1. Field of the Invention
The present invention relates to a security management method, a program, and an information device of a device such as a portable phone comprising a fingerprint authentication function, and particularly relates to a security management method, a program, and an information device comprising a fingerprint-only authentication function.
2. Description of the Related Arts
Conventionally, a fingerprint authentication function has been used in security management of portable terminal devices such as portable phones and PDAs, and a conventional fingerprint authentication function has been used in combination with a PIN code authentication function.
In the fingerprint authentication function used in combination with a PIN code, in order to recover failure in fingerprint authentication, when fingerprint authentication fails, for example, sequentially for ten times, it is switched to PIN code authentication. Therefore, even if fingerprint authentication sequentially fails due to, for example, a stain on a fingerprint sensor, since it automatically switches to PIN code authentication, the user can perform unlocking by inputting a PIN code, thereby starting, for example, applications. Furthermore, in order to prevent unlocking performed by unauthorized use, when it is switched to PIN code authentication as a result of fingerprint authentication failure, when PIN code authentication fails, for example, sequentially for five times, the power source is forcibly turned off, such that the device cannot be used any more.
However, in such conventional security management method by means of fingerprint authentication, although the power source is forcibly turned off when fingerprint authentication and PIN code authentication, which is used in combination, fail, when the power source is turned on again, fingerprint authentication and PIN code authentication can be repeatedly and sequentially performed until it reaches to a set number of failure times. If a four-digit PIN code has been set for combination use, even though a fingerprint authentication function is provided, the security performance is the same level as PIN code authentication. Therefore, there resides a problem that the high security performance by virtue of fingerprint authentication is not fully utilized.